Method of mounting a cutter upon earth boring bits



Dec. 9, 1952 PE 2,620,686

I METHOD OF MOUNTING A CUTTER UPON EARTH BORING BITS Filed July 30, 1949 Robert 6. Fe r INVEN A TTORNE Y5 Patented Dec. 9, 1952 METHOD OF MOUNTING A CUTTER UPON EARTH BORING BITS Robert G. Peter, Houston, Tex., assignor to Reed Roller Bit Company, Houston, Tex., a corporation. of Texas Application July 30, 1949, Serial No. 107,798

- 4 Claims.

This invention relates to new and useful improvements in methods of and means for mounting a cutter upon an earth boring drill bit and relates particularly to rock bit cutters of the cone-type.

In certain types of drilling, a relatively slow rotary speed of the drill pipe and bit is employed with the result that the bearing mounting for the usual bit cutter must be of suiiicient strength to withstand the severe impact loads and the axial thrusts occasioned by such drilling. Because the speed of rotation is relatively slow, the frictional characteristics of the hearing are not too important as would be the case where high drilling speeds are employed.

It is, therefore, one object of this invention to provide an improved method of and means for mounting a rotatable cutter on its journal pin or shaft whereby an exceptionally rugged bearing arrangement capable of withstanding extreme axial thrusts and. impact is produced.

An important object of the invention is to provide an improved method of mounting cone-type drilling cutters wherein the bore of the cutter is formed with a recess and wherein a portion of the journal pin or shaft on which the cutter is mounted is adapted to be deformed or displaced outwardly into the recess to thereby provide an annular bearing surface which retains the cutter upon the shaft and which also functions to carry axial thrust loads.

Still another object is to provide an improved method which consists in heating a section of a journal shaft or pin for roller cutters, inserting the shaft within the bore of a cutter and then applying sufficient force, either continuous or alternate, to deform the heated section of said shaft into a bearing recess in the wall of the bore of the cutter, whereby a bearingconnection which prevents displacement of the cutter from the shaft is produced.

A still further object is to provide an improved mountingfor cone-type rock bit cutters wherein the bore of the bit is formed with an annular recess which is adapted to coact with an annular projection or ring portion which is provided on the journal pin or shaft upon which the cutter is mounted, said annular projection coacting with the recess to provide a bearing and also to prevent displacement of the cutter from said shaft.

Other and further objects of the invention will appear from the description of the invention.

In the accompanying drawings, which form a part of the instant specification, which are to thereon.

2 be read in conjunction therewith and wherein like reference numerals are used to indicate like parts in the various views:

Figure 1 is a view partly in section and partly in elevation of a cone type bit illustrating the improved cutter mounting constructed in accordance with the invention,

Figure 2 is a vertical sectional view of one section of the bit and illustrating the first step in the method of mounting the cutter,

Figure 3 is a view similar to Figure 2 showing the cutter placed upon the journal pin or shaft, and

Figure 4 is a view similar to Figures 2 and 3 illustrating the completed assembly.

In the drawings, the numeral I6 designates a drill bit which is illustrated as the usual rock bit type having conical cutters I i mounted The bit may be constructed in any suitable manner and includes body sections A, with each of the sections A having an inwardly directed journal shaft or pin i2 disposed at its lower portion.

The present invention relates to the mounting of each cutter ii upon its journal shaft or pin i2 and as is clearly shown in Figure 2, each cutter is provided with a bore having its major portion It cylindrical and having its inner end generally tapered or conical as indicated at I4. Between the cylindrical portion I3 of the bore and the conical or tapered portion the inner wall of the cutter is formed with an annular recess or groove l5 which is preferably generally curved in cross-section. The formation of the recess provides an internal annular shoulder 6 at the inner end of the cylindrical section l3 of the bore.

The journal pin or shaft I2 is generally cylindrical and the outer diameter of the shaft is such that said shaft has a sliding or rotatable fit within the cylindrical section iii of the bore of the cutter H. An axial passage I2a may extend through the pin or shaft. The outer end of the shaft is conical or tapered in shape as indicated at I! and. this conical end is adapted to seat within the conical or tapered portion M of the cutter bore. The length of the tapered or conical surface ii of the shaft is such that when the cutter is mounted on said shaft with said conical portion engaging the taper M of the bore of the cutter, an annular space it is formed by the recess l5 and surrounds a portion of said shaft.

In mounting the cutter and carrying out the present invention an annular area B of the cylindrical shaft which is that area adjacent the conical or tapered end of the shaft is heated by any suitable heating means. Heat induction equipment may be utilized to localize the heating to the area B which is that area of the shaft which will be located opposite the annular space l8 formed by the recess 15 within the bore of the cutter. After the portion B of the shaft has been heated to the desired degree, the cutter is placed in position on the shaft as illustrated in Figure 3, and as has been stated, this locates the heated area B opposite the annular space 18 which is formed within the cutter. The cutter H is then supported in a suitable base or support C and a suitable force is applied to the section A by any suitable means, such force being in the direction of the arrows in Figure 4 which is axially of the shaft or pin it and of the cutter H. The force may be applied by any suitable means such as-a pressure rain or by a pneumatic hammering tool and the application of force to the section A will result inan upsetting of the heated area B of the shaft, whereby the material in this heated area is deformed to flow into the annular space is provided in the wall of the cutter I i. It isnoted that when the cutter is first mounted on the shaft as illustrated in Figure 2, the inner end surface of the cutter is spaced a desired distance from the annular bearing surface is provided on the sec tion A and this space allows some movement of the section A inwardly of the cutter to permit the upsetting of the area B when pressure is applied to the section as shown in Figure 4.

It will be evident that the heated area B of the shaft will be upset or deformed radially outwardly into the annular space or groove is and this upsetting will provide an integral annular rib or projection 28 on the shaft which such projection generally conforming to the cross-sectional curvature of the annular space l8. If desired, the cutter i i may be rotated on the journal pin while the upsetting of the area B is being accomplished and such rotation will preserve the alignment of the cutter relative to the shaft and will at the same time burnish the bearing surfaces between the cutter and projection. The original spacing between the inner end surface of the cutter H and the bearing surface I9 is such that when the heated area B of the shaft has been displaced into the annular space [8 formed by the recess if, the bearing surface [9 will have the desired running clearance with respect to the inner end surface of the cutter.

The deformation of a portion of the shaft 52 to provide the annular projection or rib rotatably mounts the cutter on the shaft 12 and outward displacement of the cutter from said shaft is prevented. It may be desirable to quench the heated surface B after deformation and in such instance a suitable quenching liquid may be directed to the offset or projection 28 through the axial bore 12a in the journal pin. The axial bore 12a may also be utilized to introduce a lapping or lubricating compound to the bearing surfaces between the cutter and pin 42 whereby said surfaces may be lapped or lubricated by rotating the cutter on said pin.

The mounting is extremely simple since it is only necessary to heat an annular area of the shaft and then apply suficient force to deform said heated area into the annular space or groove 18 formed within the wall of the cutter. The cross-sectional curvature or shape of the space i togetherwith the inclined or tapered coacting surfaces I4 and ll of thecutter and shaft end, 7 respectively, provide an amplified. bearing surface upon which the cutter ll may rotate. The mounting is extremely rugged, whereby extreme axial thrusts or impacts will not damage the mounting thus making the bit adaptable for efficient operation in hard formations under relatively slow rotative speeds, It is, of course, evident that the size and shape of the annular space I8 which is formed in the wall of the bore of the cutter II by the annular recess I5 is subject to variation and it is the size of this space which will determine the amount of deformation of the shaft l2 which will occur to form the annular projection 20 upon the application of force. Thus,,any size or shape of annular projection or enlargement as determined by the size and shape of the space It may be formed on the shaft. By properly controlling the initial space between the inner end surface of the cutter II and the bearing surface 19 of the section A with respect to the size or area of the annular space [8 it is possible to locate the end surface ;of the cutter in any desired spaced relationship to the-surface is when the upsetting of the shaft is complete.

From the foregoing it will be seen that this invention is one Well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having described the invention, I claim:

1. The method of mounting a drill bit cutter having a bore upon a shaft which includes, forming an annular recess in the bore of said cutter, heating a portion of the shaft in an annular path spaced from the end of the shaft, positioning said cutter on the shaft to dispose the heated portion of said shaft opposite the annular recess, and deforming the heated portion of the shaft into said annular recess, whereby an annular integral enlargement is formed on the shaft which coacts with the recess to rotatably mount the cutter on the shaft.

2. The method of mounting a cutter having a bore upon a shaft which includes, forming an annular recess in the bore of said cuttenheating a portion of the shaft in an annular path spaced from the end of the shaft, positioning said cutter on the shaft to dispose the heated portion of said shaft opposite the annular recess, and deforming the heated portion of the shaft into said annular recess by applying a force along an axial line to the shaft and cutter whereby an annular integral enlargement is formed on the shaft which-coacts with the recess to rotatably mount the cutter 'o the shaft.

3. The method of mounting a cone-type drill cutter upon the shaft of :a drill bit which includes, forming an annular recess in the wall of the boreof said cutter, heating a portion of the shaft in an annular path spaced from theend of the shaft, positioning the shaft within the bore of the cutter to locate the heated portion opposite the annular recess, and then-deforming the heated portion of the shaft into said recess to rotatably connect the cutter to the shaft.

4. The method of mounting a cone-type drill cutter upon the shaft of a drill bit which includes, farming an annular recess in the wall of the bore of said cutter, heating a portion of the shaft in an annular path spaced from the end of the shaft, positioning the shaft within the bore of the cutter to locate the heated portion opposite the annular recess, and then applying a force along an axial line to the shaft and cutter to urge the parts together and thereby deform the heated portion of the shaft into said recess to rotatably connect the cutter to the shaft.

ROBERT G. PETER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Number Name Date Davenport Feb. 25, 1913 Reed July 19, 1927 Scott et a1. Dec. 11, 1928 Wadsworth Dec. 22, 1931 Fletcher Jan. 5, 1932 Wyland Aug. 29, 1939 Neubert Apr. 27, 1943 Padley et a1. May 4, 1943 FOREIGN PATENTS Country Date Great Britain Sept. 7, 1925 

